Crack theory: what if the reason Akemura keeps malediction active on Shokoku is because, even now, 18 years later, the Mikaboshi keeps regenerating and the malediction keeps draining them (resulting at them keep being a skeleton repetitvely)🤔which means Akemura doesn't have 200,000 life force from them, he has infinity.
Akemura has kept killing them for 18 years.